What could Doctor Lessing’s obsession with the riddles suggest about how he sees life?

When Guido and Doctor Lessing rendezvous in a corner during the dinner party, Guido expects his old friend to acknowledge the gravity of his situation and help him find a way to escape from the camp. But Lessing instead asks him to help solve a riddle. Doctor Lessing was Guido's last hope of getting out of the camp alive (although it turns out that some of the prisoners do emerge alive), and the fact that the doctor is blind to Guido's reality (and humanity) is crushing to Guido. To the doctor, Guido is little more than an encyclopedia. This scene is one of the saddest and most poignant in the film: Guido is looking at the doctor, clearly hoping for a solution to his life-and-death situation, and Doctor Lessing is instead making animal noises and pleading with Guido, "Help me ... I can't even sleep." The total absence of guilt or a sense of responsibility condemns Guido to almost certain death, but the doctor does not realize this, being wholly obsessed with a trivial riddle. The incongruity of Guido's dire situation and the doctor's priorities is shocking, revealing the degree to which the doctor is also out of touch with reality. He is either retreating from the traumatic truth of the Fascists' treatment of the Jews, or he simply has a dangerous inability to empathize with others. In either case, his character symbolizes the myriad ways in which individuals contributed to the horrors of the Holocaust: some by directly perpetuating acts of evil, and others by simply standing idly and doing nothing to help.